Development And Experiment Of High Frequency Pulse Power Supply For Electrochemical Machining

Electrochemical machining(ECM)technique is an electrochemical process in which metal workpiece is dissolved under high pressure and high flow rate electrolyte flushing.ECM has the unique advantages of high processing efficiency,good surface quality,independent of material hardness,and no tool cathode loss.It has become a key processing technology in the fields of aerospace,weaponry,etc.Pulse power supply is a key component of ECM equipment and its voltage value,waveform,voltage regulation accuracy and short-circuit protection have a direct impact on the electrochemical machining process.Based on the analysis of characteristics of electrochemical machining process and the mechanism of pulse current electrochemical machining,the overall structure of high-frequency pulse power supply is designed by using the DC-chopper topology scheme,and the electrochemical hole drilling test is carried out to verify the function of the developed pulse power supply.The primary research contents of this paper including:1.Development of digital high-frequency pulse power system.The stable output of DC circuit with adjustable value is realized through the specific design of the pre-stage circuit.Under the design method of positive and negative power supply,the stable output of positive and negative pulse current with adjustable parameters is realized through the design of the chopper circuit based on the on/off of the power switch tube.Based on the digital functional requirements of pulse power supply,the control system is specifically designed to realize functions such as pulse generation,data acquisition,and serial communication;2.Design and implementation of short-circuit protection system.Based on the preset value protection strategy,a follow-up reference voltage comparison method is proposed as an additional protection strategy of fast short-circuit protection system,and through changing the initial value of the reference voltage,the sensitivity of the detection loop could be adjusted to adapt to the short-circuit protection response under different conditions.In order to eliminate the residual charge of the cathode and the anode in time,a quick release circuit is designed to effectively prevent burns on tools and workpieces.3.Experimental study on verification of electrochemical hole drilling.The pulse power supply is used for the electrochemical hole drilling.The performance of short-circuit protection function and the negative-polarity pulse function are analyzed by a single factor test method.The orthogonal testdesign method is used to analyze the influence of machining voltage,frequency and duty cycle on aperture,and finally a set of optimal parameters are selected for processing group hole.Through multiple sets of tests,the output performance of the pulse power supply is verified to meet the requirements of electrochemical machining,and the stability of the developed pulse power supply under long-term operation conditions is also verified.